Coastal archaeological sites dating to the late Pleistocene and early Holocene are rare on the northwest coast of North America, as they are in many regions of the world, due to changing environmental factors, in particular glacial isostasy and eustasy, resulting in low visibility and survival of archaeological deposits. This dissertation outlines methods and results used to locate late Pleistocene and early Holocene archaeological sites on the Dundas Island Archipelago on the Northwest Coast culture area of British Columbia, Coast Tsimshian Territory, where archaeological sites older than 5,000 years BP are not known. Part of the reason for this is that masses of glacial ice accumulated on the Cordilleran Mountains of North America during the last glacial maximum, which depressed mainland coastal regions isostatically in relation to sea levels. As a result of lateral displacement of subcrustal material, areas to the west of the Cordillera bulged and landforms were raised relative to the sea. With deglaciation, the depressed crust began to rebound and the forebulge subsided resulting in rapidly dropping sea levels along the mainland to the east and rapidly rising sea levels along outer coastal islands to the west. These processes occurred in concert with sea levels that began rising eustatically following the last glacial maximum. Between the inner and outer coasts lies the Dundas Island Archipelago. This research project hypothesized that the study area was close to a sea level hinge lying between these two regions with very different sea level histories. With less significant shoreline movement, it was further anticipated that shoreline situated archaeological sites dating to the late Pleistocene and early Holocene might be found in close proximity, although slightly higher than the present day shoreline. This dissertation addresses the following question: Where are late Pleistocene and early Holocene archaeological sites situated on the Dundas Island Archipelago? To address this question, this dissertation details the methods and results used to determine a sea-level and vegetation history for the Dundas Island Archipelago and the archaeological prospection that was undertaken along relict shorelines. Pollen analysis of sediments from a lake core identified a sequence of six vegetation zones beginning before 12,385 BP. Based on diatom identification of cores from four lake basins, combined with supporting indicators, a sea level curve for the Dundas Islands was constructed showing a slow regression of shorelines from 13 m above the barnacle line to present day elevations over the last 12,000 years BP. Drawing upon these palaeo-environmental data, areas were selected for archaeological survey and prospection. Field testing of these selected areas resulted in the identification of five archaeological sites dating to the early Holocene. These are the first archaeological sites dating older than 5,000 years BP that have been found and dated in Coast Tsimshian Territory. The elevations and radiocarbon dates on all archaeological deposits are consistent with the sea level curve based on palaeo-environmental data points. Overall, this dissertation draws upon palaeo-environmental methods and results for the purpose of identifying and interpreting archaeological sites situated on raised marine landforms.

The sediment Core SWERUS-L2-2-PC1 (2PC) retrieved from the Chukchi Sea, Arctic Ocean sits in an oceanographically dynamic location at the Arctic-Pacific Ocean gateway. The 8.3 m-long core was retrieved in Herald Canyon at the marginal ice zone at 57 m depth. Core 2PC is well-positioned to record variability in inflow of Bering Sea Water (BSW) and Pacific Water (PW) in Herald Canyon. With the 2PC high sedimentation rate (200 cm/kyr), two independent age models (radiocarbon and palaeomagnetism) based on tephra age markers, and a richness in well-preserved siliceous sediment, validate 2PC as an outstanding sequence for applying diatom assemblage analysis as a proxy for ocean-climate change back to 4250 years BP, including the past few hundred years where global warming and sea ice decline is recorded by instrumental records. These characteristics make Core-2PC a useful record for investigating the role of PW on sea ice variability in the Chukchi Sea, both in the past and predicting the future. To investigate the impact of PW on ocean and sea ice conditions in the Chukchi Sea, diatom assemblage analysis was performed on 49 samples through the Late Holocene. The over-arching goal was to test the hypothesis, suggested by existing research on 2PC using benthic foraminifera Mg/Ca palaeothermometry, that the strength of PW inflow into the Chukchi Sea via Herald Canyon has varied on a time scales of ~500-1000 years in the past 4000 years. PW is slightly warmer than resident Arctic surface waters and is known to be an important control on Arctic sea-ice. The diatom assemblage approach assumes that there are recognizable differences between end-member diatom assemblages that are characteristic of PW versus Arctic Ocean type environments associated with extensive sea-ice conditions. The mapping of species in the Herald Canyon was used to test the idea of variability of sea-ice extent and the role of the Pacific Ocean forcings into the western Chukchi Sea. The results reveal diverse diatom assemblages throughout the past 4000 years in Herald Canyon, showing this core to be very useful for diatom palaeoclimate reconstructions. A total of 126 species with abundance >1% are recognized. Several generalist species typically dominate assemblages especially Chaetoceros, ice-algae, marine-neritic and near ice or cold-water planktic centric diatoms. Distinct changes in stratigraphy are illustrated by changes in identified diatom assemblage zones. The 2PC diatom assemblages were contrasted with records from Chukchi-, Laptev-, East Siberian- and Bering Sea and North Pacific Ocean. At 2PC, sympagic (sea-ice related), planktic and neritic species abundance varies on time scales of ~500-1000 years. Importantly, there is a clear similarity between the timing of diatom assemblage changes and the 2PC benthic foraminifera Mg/Ca bottom water temperature (BWT) reconstruction. In particular, abundance changes in the warm water species Thalassionema nitzschioides, Shionodiscus oestrupii and Thalassionema simonsenii, tychoplanktic Paralia sulcata, Ice algae- and sympagic assemblages and cold-water indicators correspond best to BWT fluctuations shown by the Mg/Ca reconstruction. These oscillations are suggestive of changes in warmer PW inflow. Other aspects of the diatom data appear to correlate with colder and warmer climate events and suggest that changes in PW inflow amplified the effects of these events in the Chukchi Sea region through the Late Holocene in the Northern Hemisphere. It can thus, be concluded that diatoms from 2PC, support the palaeoceanographic reconstruction suggested by the benthic foraminifera Mg/Ca palaeothermometry and that variations in PW inflow through Herald Canyon is an important driver of sea ice variability on thousand-year time scales.

[ES] Los biosensores son dispositivos analíticos con aplicabilidad en diferentes campos y con numerosas ventajas frente a otros métodos analíticos convencionales, como son el uso de pequeños volúmenes de muestra y reactivos, su sensibilidad y su rápida respuesta, sin necesidad de pretratamiento de la muestra, equipos caros o personal especializado. Sin embargo, se trata de un campo de investigación relativamente nuevo en el que todavía queda mucho camino por andar. Esta Tesis doctoral pretende aportar un granito de arena a este campo de conocimiento mediante el estudio del potencial de diferentes materiales porosos como transductores para el desarrollo de biosensores ópticos con respuesta en tiempo real y sin marcajes. Los materiales propuestos van desde aquellos artificialmente sintetizados, como silicio poroso (SiP), nanofibras (NFs) poliméricas o membranas poliméricas comerciales, hasta materiales naturales con propiedades fotónicas que todavía no habían sido explotadas para el sensado, como son los exoesqueletos de biosílice de diatomeas. Todos ellos tienen en común la simplicidad en su obtención, evitando costosos y laboriosos procesos de nanofabricación. Para su estudio, se analizará su respuesta óptica y, en aquellos casos en los que ésta permita llevar a cabo experimentos de detección, se desarrollarán estrategias para su biofuncionalización y su implementación en experimentos de biosensado. En el caso del SiP y las NFs se han optimizado los parámetros de fabricación para obtener una respuesta óptica adecuada que permita su interrogación. A continuación, se ha llevado a cabo su biofuncionalización empleando métodos covalentes y no covalentes, así como diferentes bioreceptores (aptámeros de ADN y anticuerpos) para estudiar su potencial y sus limitaciones como biosensores. En el caso de las membranas comerciales y el exoesqueleto de sílice de diatomeas, se ha caracterizado su respuesta óptica y se han llevado a cabo experimentos de sensado de índice de refracción para estudiar su sensibilidad. Así mismo, se ha desarrollado un método de funcionalización de la superficie del exoesqueleto de diatomeas basado en el uso de polielectrolitos catiónicos. Como resultado, se ha demostrado el potencial tanto de NFs para el desarrollo de biosensores, como el de membranas comerciales para sensores cuya aplicación no requiera una elevada sensibilidad pero sí un bajo coste. Además, se ha puesto de manifiesto el gran potencial del exoesqueleto de diatomeas para el desarrollo de sensores basados en su respuesta óptica. Por el contrario, las limitaciones encontradas en el desarrollo de biosensores basados en SiP han evidenciado la necesidad de un estudio riguroso y la optimización de la estructura de materiales porosos previamente a ser usados en (bio)sensado. / [CA] Els biosensors són dispositius analítics amb aplicabilitat en diferents camps i amb nombrosos avantatges enfront d'altres mètodes analítics convencionals, com són l'ús de xicotets volums de mostra i reactius, la seua sensibilitat i la seua ràpida resposta, sense necessitat de pretractament de la mostra, equips cars o personal especialitzat. No obstant això, es tracta d'un camp d'investigació relativament nou en el qual encara queda molt camí per fer. Aquesta Tesi doctoral pretén aportar el seu òbol a aquest camp de coneixement mitjançant l'estudi del potencial de diferents materials porosos com a transductors per al desenvolupament de biosensors òptics amb resposta en temps real i sense marcatges. Els materials proposats van des d'aquells artificialment sintetitzats, com a silici porós (SiP), nanofibras (NFs) polimèriques o membranes polimèriques comercials, fins a materials naturals amb propietats fotòniques que encara no havien sigut explotades per al sensat, com són els exoesquelets de biosílice de diatomees. Tots ells tenen en comú la simplicitat en la seua obtenció, evitant costosos i laboriosos processos de nanofabricació. Per al seu estudi, s'analitzarà la seua resposta òptica i, en aquells casos en els quals aquesta permeta dur a terme experiments de detecció, es desenvoluparan estratègies per a la seua biofuncionalizació i la seua implementació en experiments de biosensat. En el cas del SiP i les NFs s'han optimitzat els paràmetres de fabricació per a obtenir una resposta òptica adequada que permeta la seua interrogació. A continuació, s'ha dut a terme la seua biofuncionalizació emprant mètodes covalents i no covalents, així com diferents bioreceptors (aptàmers d'ADN i anticossos) per a estudiar el seu potencial i les seues limitacions com a biosensors. En el cas de les membranes comercials i l'exoesquelet de sílice de diatomees, s'ha caracteritzat la seua resposta òptica i s'han dut a terme experiments de sensat d'índex de refracció per a estudiar la seua sensibilitat. Així mateix, s'ha desenvolupat un mètode de funcionalizació de la superfície de l'exoesquelet de diatomees basat en l'ús de polielectròlits catiònics. Com a resultat, s'ha demostrat el potencial tant de NFs per al desenvolupament de biosensors, com el de membranes comercials per a sensors amb una aplicació que no requerisca una elevada sensibilitat però sí un baix cost. A més, s'ha posat de manifest el gran potencial de l'exoesquelet de diatomees per al desenvolupament de sensors basats en la seua resposta òptica. Per contra, les limitacions trobades en el desenvolupament de biosensors basats en SiP han evidenciat la necessitat d'un estudi rigorós i l'optimització de l'estructura dels materials porosos prèviament a ser usats en (bio)sensat. / [EN] Biosensors are analytical devices with application in diverse fields and with several advantages relative to other conventional methods, such as the use of small volumes of sample and reagents, their sensitivity and their fast response, without the need of the sample pretreatment, expensive equipments or specialised technicians. Nevertheless, this is a relatively new research field in which there is a long way to go yet. This doctoral Thesis aims at doing its bit to this field of knowledge by studying the potential of different porous materials as transducers for the development of real-time and label-free optical biosensors. The proposed materials range from those artificially synthesised, such as porous silicon (pSi), polymeric nanofibres (NFs) or commercial polymeric membranes, to natural materials with photonic properties that had not been exploited for sensing yet, such as biosilica exoskeletons of diatoms. All of them have in common its simple production, avoiding expensive and laborious nanofabrication processes. For their study, their optical response will be analysed and, in those cases in which such optical response allows performing detection experiments, strategies for their biofunctionalisation and their implementation in biosensing experiments will be developed as well. Regarding pSi and NFs, the fabrication parameters were optimised to get a suitable optical response for their interrogation. Afterwards, their surface functionalisation was carried out by covalent and non-covalent methods, as well as different bioreceptors (DNA aptamers and antibodies), to study their potential and their constraints as biosensors. Concerning commercial membranes and the biosilica exoskeleton of diatoms, their optical response was characterised and refractive index sensing experiments were carried out to study their sensitivity. Additionally, a biofunctionalisation method for the surface of the diatoms exoskeleton was developed based on the use of cationic polyelectrolytes. As a result, it was demonstrated the potential of NFs for the development of biosensors, as well as the potential of commercial membranes for developing sensors for an application that does not require a high sensitivity but a low cost. Furthermore, the great potential of biosilica exoskeleton of diatoms for the development of sensors based on their optical response has been revealed. By contrast, the constraints found in the development of pSi illustrate the importance of an accurate study and optimisation of porous materials structure before using them for (bio)sensing. / Martínez Pérez, P. (2021). Development and Optimization of Experimental Biosensing Protocols Using Porous Optical Transducers [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/172541

Sedimentation rates and compositions of sinking particles were investigated at three sites on the Beaufort slope and one in Canada Basin during the period 1990-1994 using moored sequential sediment traps. A method was developed to identify the terrigenous and biogenic components of the fluxes. The physical context including ice cover, ocean currents, river inputs, winds, air temperature, incident light, and nutrient availability provide essential information to the interpretation of the particle fluxes and to the understanding of shelf-basin sediment transport in this area. Eddies, internal waves, upwelling and downwelling, and the state of the ice cover all played important and overlapping roles in the pattern of observed fluxes. A peak in the flux of highly terrigenous material under complete ice cover in mid-winter to the northwest of Mackenzie Trough was associated with predominantly downwelling conditions and the passage of a series of eddies and internal waves. A prolonged spring diatom bloom occurred in the mid-slope area and was clearly associated with an early opening of the ice on the east side of the shelf. Higher fluxes at the Canada Basin site were associated with a large eddy clearly identifiable from the current-T-S record and also from the composition of the suspended material carried with it. At the base of the slope (2700 m), the composition was highly terrigenous and remarkably consistent. Higher up the slope (700 m), biogenic peaks in the summer diluted the terrigenous material briefly, but it appears that there is a constant background of highly terrigenous material. There was a high degree of variability between sites and over the slope there was not enough data to asses the inter-annual variability. In Canada Basin, the inter-annual variability was closely linked to the extent of open water in the summer period. At all sites, lateral transport is clearly indicated by the increase in flux with depth. The data robustly demonstrate the need for detailed knowledge of physical processes for informed interpretation of particle fluxes and sediment transport in this area.

Since 1750, human emissions of greenhouse gases have created a temperature increase, affecting the whole world. Diatoms, single-celled microscopic algae that lives in waters all over the world, have different environmental preferences such as the water depth at which the thrive, salinity, nutrients, pH-values and more. Diatoms also responds quickly to changing circumstances, which makes the suitable as environmental indicators. The purpose of the study is to investigate how the abundance and composition of diatoms has changed during the last 200 years in lake Ensjön, located just south of Norrköping, and to relate those changes both to climate change and known events and environmental factors in the area.  The survey is conducted by subsampling sediment cores from which each diatom sample was prepared in accordance with the scheme of Battarbee (1984). The diatoms in the samples were counted under a microscope and the results were analyzed and related to the Cyclotella-Aulacoseira-Fragilaria-theory (CAF) and documented historical events in the local environment. The result of the analysis shows that the composition and abundance of diatoms has changed during the last 200 years, and that this change is due to both climate change (temperature and precipitation increase) and the land-use history of Ensjön. The cahnges in composition of Aulacoseira spp. and Cyclotella spp., where Aulacoseira spp. is expected to decrease, and Cyclotella spp. is expected to increase with a rising temperature, match the CAF-theory for the most part. The change in composition also coincides with several documented environmental factors in the area, especially the change in use of fertilizers and herbicides in agriculture. / Människans utsläpp av växthusgaser har sedan år 1750 skapat en temperaturökning som går allt snabbare, och påverkar hela världen. Kiselalger, encelliga mikroskopiska alger som lever i vatten över hela världen, har olika miljöpreferenser såsom bland annat på vilket vattendjup de trivs, optimal halt av salt, näringsvärden, pH-värden, samt reagerar snabbt på förändrade omständigheter, vilket gör dem lämpliga som miljöindikatorer. Syftet med studien är att studera förändringar i kiselalgernas sammansättning under de senaste 200 åren i den lilla sjön Ensjön belägen något söder om Norrköping och att relatera dessa förändringar till dokumenterade händelser och miljöfaktorer i sjöns avrinningsområde samt till de pågående klimatförändringarna.  Undersökningen är utförd genom provtagning av sedimentkärnor från vilka prover preparerades enligt Battarbees (1984) flödesschema. Proverna av kiselalger räknades under mikroskop och sammansättningen analyserades utifrån teorin Cyclotella-Aulacoseira-Fragilaria (CAF) och kända historiska händelser i närmiljön. Analysresultatet visade att kiselalgssammansättningen har förändrats under de senaste 200 åren, och att denna förändring sannolikt kan kopplas både till klimatförändringar (en ökad temperatur) och Ensjöns markanvändningshistoria. Förändringen hos Aulacoseira spp. och Cyclotella spp. följer till stor del CAF-teorin om att det första släktet skulle minska och det andra skulle öka vid en temperaturökning. Vid flera tillfällen sammanfaller förändringar i kiselalgssammansättningen med kända miljöfaktorer i närmiljön, främst i samband med utvecklingen i användningen av mineralgödsel och växtskyddsmedel.